# Forms

**Warning:** This document is for an old version of Rasa. The latest version is 1.10.26.

## Forms

Note  
There is an in-depth tutorial [here](https://blog.rasa.com/building-contextual-assistants-with-rasa-formaction/) about how to use Rasa Forms for slot filling.

### Configuration File

To use forms, you also need to include the `FormPolicy` in your policy configuration file. For example:

```
policies:
  - name: "FormPolicy"
```

### Form Basics

Using a `FormAction`, you can describe _all_ of the happy paths with a single story. By “happy path”, we mean that whenever you ask a user for some information, they respond with the information you asked for.

```yaml
## happy path
* request_restaurant
    - restaurant_form
    - form{"name": "restaurant_form"}
    - form{"name": null}
```

### Custom slot mappings

If you do not define slot mappings, slots will be only filled by entities with the same name as the slot that are picked up from the user input. Some slots, like `cuisine`, can be picked up using a single entity, but a `FormAction` can also support yes/no questions and free-text input. The `slot_mappings` method defines how to extract slot values from user responses.

```python
def slot_mappings(self) -> Dict[Text, Union[Dict, List[Dict]]]:
    return {
        "cuisine": self.from_entity(entity="cuisine", not_intent="chitchat"),
        "num_people": [
            self.from_entity(
                entity="number", intent=["inform", "request_restaurant"]
            ),
        ],
        "outdoor_seating": [
            self.from_entity(entity="seating"),
            self.from_intent(intent="affirm", value=True),
            self.from_intent(intent="deny", value=False),
        ],
        "preferences": [
            self.from_intent(intent="deny", value="no additional preferences"),
            self.from_text(not_intent="affirm"),
        ],
        "feedback": [self.from_entity(entity="feedback"), self.from_text()],
    }
```

### Validating user input

After extracting a slot value from user input, the form will try to validate the value of the slot.

```python
def validate_cuisine(
        self,
        value: Text,
        dispatcher: CollectingDispatcher,
        tracker: Tracker,
        domain: Dict[Text, Any],
    ) -> Dict[Text, Any]:
        if value.lower() in self.cuisine_db():
            return {"cuisine": value}
        else:
            dispatcher.utter_message(template="utter_wrong_cuisine")
            return {"cuisine": None}
```

### Handling unhappy paths

Of course your users will not always respond with the information you ask of them.

```yaml
## chitchat
* request_restaurant
    - restaurant_form
    - form{"name": "restaurant_form"}
* chitchat
    - utter_chitchat
    - restaurant_form
    - form{"name": null}
```

### The requested_slot slot

The `requested_slot` is automatically added to the domain as an unfeaturized slot.

### Handling conditional slot logic

You can achieve this by writing some logic into the `required_slots()` method, for example:

```python
@staticmethod
def required_slots(tracker) -> List[Text]:
   if tracker.get_slot('cuisine') == 'greek':
     return ["cuisine", "num_people", "outdoor_seating", "preferences", "feedback"]
   else:
     return ["cuisine", "num_people", "preferences", "feedback"]
```

### Debugging

The first thing to try is to run your bot with the `debug` flag, see [Command Line Interface](https://legacy-docs-v1.rasa.com/1.10.5/user-guide/command-line-interface/#command-line-interface) for details.

👋 I can help you get started with Rasa and answer your technical questions.